TROPICAL STORM UPDATE AS OF 5-24-18 AT 9AM:

Tropical Update
9 AM EDT
Thursday, May 24, 2018
Invest Area 90L (80%)
This update is intended for government and emergency response officials, and is provided for
informational and situational awareness purposes only. Forecast conditions are subject to
change based on a variety of environmental factors. For additional information, or for any life
safety concerns with an active weather event please contact your County Emergency
Management or Public Safety Office, local National Weather Service forecast office or visit the
National Hurricane Center website at www.nhc.noaa.gov.
A disturbance near the Yucatan Peninsula will drift northward this weekend into the Gulf of
Mexico. There remains some uncertainty with the track and intensity of the system, but will still
result in a wet pattern continuing to affect Florida for the next several days.
Chance of Development within 48 hours = 40%
Chance of Development Saturday-Tuesday = 80%
Caribbean/Gulf Satellite Image
Thunderstorm activity has increased, but is still
displaced to the east of the center. Once the
low moves into the Gulf of Mexico, additional
development is likely.
Steering Currents
Steering currents near 90L remain very weak, thus a
continued slow northward movement is expected for
the next several days.
Forecast Weather Map – This Weekend
90L will slowly move
northward towards
the central Gulf Coast
through Memorial
Day, but showers and
storms will spread
well to the east of the
center and affect
much of Florida.
Showers and storms
may begin to affect
South Florida Friday
morning and spread
northward into North
and Central Florida
throughout the day on
Saturday.
Widespread
showers and
storms will affect
all of Florida
Sunday.
Showers and storms will
linger through Monday
for much of the state,
with additional lingering
storms activity expected
along the Florida Gulf
Coast on Tuesday.
Current Wind Shear (shaded) and
Shear Tendency (lines)
Moderate to high
wind shear in the Gulf
will initially limit
intensification, but
shear is now expected
to decrease by
Sunday, allowing for a
better chance of
intensification as it
approaches the
northern Gulf Coast.
Observed Rainfall Over Past 7 Days
All of Florida has had well
above normal rainfall
over the past 7-10 days.
This results in saturated
grounds that will reduce
the amount of time and
rain needed to create
flood conditions.
Above Normal
Flow
Normal Flow
Below Normal Flow
Many West Central Florida and some Panhandle
rivers are now at above normal flow, meaning
additional rainfall may cause flooding issues.
Forecast Total Rainfall Accumulations for next 2 Days
Soggy conditions will continue this week with rain amounts of 1-3” over the next 2
days.
Forecast Total Rainfall Accumulations
The rain from 90L will begin to affect South Florida on Friday into Saturday and
spread northward through the weekend. With the possibility of this system stalling
over the Southeast U.S., additional rainfall may continue into the middle of next
week.
Saturday Sunday-Monday
Forecast Total Rainfall Accumulations for next 7 Days
EXACT RAINFALL AMOUNTS WILL DEPEND ON THE STRUCTURE AND TRACK OF 90L, WHICH COULD BE HIGHER THAN
WHAT IS SHOWN. At this time, widespread average rainfall amounts of 3-6” inches are possible statewide, with isolated
higher totals of 7 to 13 inches possible over portions of the Panhandle and Southeast Florida. This should result in street
flooding and river flooding, especially in areas where several storms repeatedly move over the same area.
• Since soils are
already saturated,
any additional
heavy rain
(generally 3-4” in
less than 3 hours)
will cause flash
flooding issues.
• Lower amounts, or
3-6” over a longer
time period can still
cause flooding of
roads and low-lying
areas.
• Note:
hydrograph
forecasts only
account for
anticipated
rainfall over the
next 48 hours.
Although a
recession is
forecast,
additional rises
this weekend
are likely.
In addition to the flash flooding
potential, minor to moderate
flooding on area rivers will be
possible, but this will ultimately be
dependent on where the
heaviest rain falls. The areas for
concern are currently in West
Central Florida, the Florida
Panhandle, and the Santa Fe River
basin and Paynes Prairie State Park.
Summary • A broad surface low (Invest 90L) centered over the Yucatan Peninsula is gradually getting better organized.
• Continued development is expected once the system moves into the southern Gulf of Mexico by Saturday morning, and
environmental conditions are forecast to become more conducive for development in the central and northern Gulf of Mexico
over the weekend.
• As a result, the National Hurricane Center is now predicting a 40% (medium) chance of 90L becoming a tropical depression or
storm within the next 48 hours, and an 80% (high) chance of becoming a tropical cyclone within the next 3-5 days.
• Although computer models are getting into better agreement, there is still a fair amount of uncertainty with regard to the
track, intensity and timing of the system.
• The low pressure system should reach the northern Gulf coast region on Sunday or Monday (a day later than previously
forecast) and then linger over the region into the early part of next week, increasing the rainfall totals and threat for flooding.
• If named, the first name on the 2018 Atlantic Storm name list is Alberto.
Florida Outlook:
• Regardless of track or intensity, this system will result in a multi-day widespread rainfall event that may impact a large portion
of Florida, mainly Friday-Sunday across South Florida and Saturday through at least next Wednesday for North Florida and
portions of Central Florida.
• There are currently no watches or warnings, but Flood Watches, Flash Flood Watches, Coastal Flood Watches and High Surf
Advisories may be issued by Friday.
• Widespread rainfall amounts of 3-6” are expected statewide, with locally higher amounts of 7-12+” possible, especially for the
Florida Panhandle and possibly West Coast of Florida.
• River flooding will also be a concern for portions of the state, especially in West Central Florida, North-Central Florida and the
Florida Panhandle/Big Bend.
• Increased wave heights are also expected along the Panhandle and East Coast and will lead to a high risk of rip currents for the
holiday weekend.
• Any other possible impacts late this week through early next week (wind, tornadoes, and surge) will depend heavily on how
this system evolves and more information will be available in the coming days.
Another briefing packet will be issued this afternoon. For more information on this system visit the NHC website at
www.nhc.noaa.gov
Tropical Update
Created by:
Amy Godsey, Chief State Meteorologist
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State Meteorological Support Unit
Florida Division of Emergency
Management
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